Heat transfer



June 27, 1961 R. G. SHEPHERD, JR 2,990,311

HEAT TRANSFER Filed Jan. 9, 1956 tates This invention relates to the artof heat transfer and particularly to heat transfers for applying labelsand designs to thin, impervious films.

In many packaging operations involving packaging film such astransparent plastic sheetsit is desired to apply identifying labels ordecorative designs to the finished package. This has heretofore beenaccomplished by preprinting the film or by applying separate paperlabels. Preprinting is normally accomplished by processes such as'exography, rotogravure or silk screen which require elaborate andexpensive equipment. Packaging concerns normally have this printing doneby outside contractors which procedure is expensive and requires themaintenance of expensive inventories. Further, in packaging foodstulfs,conventional printing cannot usually be tolerated immediately prior topackaging because of the danger of food contamination by fresh inkodors. Where a variety of goods are packaged it is often more expedientand less expensive to use unprinted lm and to label by alixing separatepaper labels. In many instances these paper labels do not present asattractive an appearance as the more expensive printed film. In additionsuch labels have a tendency to cause wrinkles and to fray and curl atthe edges and to come loose.

Heat transfer compositions heretofore disclosed for marking purposeshave been defective in one or more respects which has limited orprevented their use for labeling impervious film. These priorcompositions can be classified under two general types: (l) those inwhich a heat responsive image, or image-forming coating lies directly ona backing or temporary carrier, and (2) those in which the image isprinted on a heat-responsive transfer coating which lies on a backing.

Heat transfer processes falling under the rst category, referred toabove, include roll leaf marking whereby a heated printing plate causesa pigmented coating to transfer opposite areas where heat and pressureare applied. This process does not permit line `detailed printing, isnot applicable to half tone reproduction and is expensive and unwieldyfor multi-color printing. Other compositions falling under the firstcategory include special thermoplastic ink images deposited on a carrierpaper. These products are commonly used for decorating porous receivingsurfaces such as textile and wood and either dis'- tort when used inconjunction with impermeable receiving surfaces or are of limitedutility for fine detailed work due to the heavy ink layers required.Further, they have a tendency to only partially transfer and leave partof the image on the backing. Generally these image materials are notamenable to application on conventional printing equipment. Due to theabsence of a protective transfer layer, all of the processes fallingunder this first category are sensitive to abrasions and cannot be usedfor underside labeling of films for food packaging because of the dangerof contamination.

Certain of the above deficiencies have been overcome by using heattransfer processes of the second general category wherein a heatresponsive transfer layer is provided. Thus nely detailed, multi-coloredimages can be printed on the transfer layer by conventional processes.The resulting print, which is usually thin and very delicate, isprotected from distortion during transfer by the strong transfer lfilm.The presence of the transfer lm insures the complete transfer of theimage. After trans- Patented June 27, 1961 "ice the printed transferlayer are sharply transferred opposite' area where heat and pressure areapplied. This lack of sharp breakaway property in previously disclosedcompositions can be attributed to the film strength of the high polymersin the transfer coating, which causes a ragged outline at the border ofapplication of heat and pressure. This diiculty can be overcome byapplying the transfer coating in discrete areas of label size but thisconstitutes a complicated coating process and requires careful printingregistration which increases the cost materially. Sharp breakawayproperties are a necessity for high speed label applications Where thearea of the label is less than the area of the receiving surface.

A further disadvantage ofheat transfers heretofore disclosed under thesecond category is the relatively high activation temperature requiredto effect adhesion to the receiving surface. Attempts have been made tocorrect this by the application of separate adhesive layers over theprinting as in the case of heat transfer decalcomanias. This alsoincreases cost, requiresv special coating equipment and does not permitthe application of last minute price and code information.

It is accordingly one object of the present invention to provide aninexpensive process and materials to apply high quality, printedtransfers to film only opposite those areas where heat and moderatepressure are applied. Another object is to provide a process andmaterials for labeling impervious film which combines the attractivenessof preprinted ilm with the low cost and flexibility of separate paperlabels. Still another object is to provide for the last minute additionof prices and code designations. Further objects are to provide aprocess and materials for labeling impervious film which requiresrelatively simple equipment, which permits simple machine application,which will not cause wrinkles in the film, which lowers the thermalactivation temperature, which puts the label in optical contact with thetransparent film `and utilizes the glossy surface of the film to presentan attractive appearance and to present an abrasion resistant andtamperproof label, and which provides a method for labeling anddecorating flexible and extensible film.

Other objects and advantages will be apparent from the followingdisclosure.

According to the present invention the above objects are achieved byproviding a heat transfer which cornprises a backing coated with atransfer layer and a design printed o-n the transfer layer by ordinarycommercial methods. The transfer layer comprises a uniform mixture of acrystalline Wax and a synthetic, thermoplastic, film-forming, resinwherein each ingredient is present to the extent of at least 15% oftheir combined weights. The resins preferred for the present inventionare synthetic, linear, polymeric, principally organic, thermoplastic,substantially water-insoluble, and which have a second-order transitiontemperature below approximately 60 C. while the preferred waxes have amelting point between about 50 C. and 110 C. and a penetrometer value(ASTM D5-52) below about 15 when tested with grams weight for 5 secondsat 25 C.

In a particular aspect the compatibility of the resin and wax iscontrolled through selection and ratios of ingredients to give heattransfers of either the hot peel or the cold peel type. A cold peeltransfer is one Wherein the transfer 4layer carrying a design willadhere to the receiving surface when hot but will only release andtransfer by peeling away the backingV after the transfer has cooled. Ahot peel transfer is a transfer wherein the transfer will adhere andrelease from the backing only immediately after application while thetransfer isstill hot. In both types, resins and waxes areselected whichare mutually incompatible or insoluble at temperatures below the meltingtemperature of the wax such that the molten Wax, upon cooling, willcrystallize separately and distinctly from the resin.` Hot peeltransfers are provided by selecting resins and waxes which are alsoincompatible or of low mutual solubility at temperatures above themelting point of the wax. Cold peel transfers are provided by selectingresins and waxes which are substantially compatible at temperaturesabove the melting temperature Vof the Wax. Each of these types areuseful for particular purposes as hereinafterV set forth.

The present invention may be better understood by reference to theaccompanying drawing in which Y FIG. l is an isometric view of the heattransfer of the present invention; Y

FIG. 2, is a cross-sectiion on the line 2 2 of lFIG. l; FIG. 3 is anisometric view of the present transfer after it has been aiiixed to thepackaging film; and

FIG. 4 is a cross-section on the line 4-4 of FIG. 3.

In accordance with the present invention a backing sheet l is coatedwith a transfer coating 11, specially prepared as set forth below. Theexposed surface of the transfer layer is then printed with the desiredlabel or design 12. The transfer coating is printed by any of thecommercial methods used for printing paper. Thus the design 12 may be ofany type or color or combination thereof available in the graphic arts,yielding to great variety of designs at minimum cost on existingequipment.

The design y12 is aiiixed to the packaging film 13 by placing the designside of the heat transfer against the Iiilrri and applying heat andmoderate pressure. The backing sheet 10 is then stripped away leavin-gthe design 12 and the transfer layer 11 lfirmly attached to the iilm.Thus the design 12 is permanently sandwiched between the film 13 and thetransfer layer 111. This is advantageous since the glossy surface of thefilm enhances the attractiveness of the design and any food contained inthe packaging film is protected by the transferV layer 11 fromcontamination with design materials of questionable toxicity.

Theboundaries of the transfer -film` areV defined by the outline of theapplication of the heat which can be accomplished by means of an iron orother heated surface. Thus the design can be of any configurationdesired by the use of n suitably shaped heating surface. The area heatedwill transfer completely while the adjace'n't unheated areas' willremain attached to the backing and 'a sharp line of separationisachieved. The heat is'preferably applied in a rolling motion 4topreclude lthe formation of bubbles and air pockets. The heating surfacecan be applied either to the backing or to the backof the receivingsurface. Where the receiving surface is thin iilm, lower heating'temperatures are possible Where the heat is applied through the back ofthe film.

Any suitable materal may be used as the 'backing whichserves merely asamechanical support. Paper is preferred' for economic reasons and isquite satisfactory. The backing should be relatively non-adhesive to thetransfer layer to allow preferential adherence to the receiving surface.Some papers are suliciently smooth t'o' serve without further Vtreatmentwhile Vothers may be rendered satisfactory 'by the use of sizingslEmulsions of waxes and low molecular weight polyethylene have been foundto be particularly suitable for the present invention. Examples are setforth below as release papers A, B, C and D.

RELEASE PAPER A Nine lbs. of Duroxon H-110, an emulsiiiable hardFischer-Tropsch wax, melting above C., sold by Dura Commodities Corp.,isV melted and mixed with 2.4 lbs. of morpholine. The mixture is pouredinto 51 lbs. of boiling waterand cooled with agitation. The resultingemulsion is coated on a 26 lb. (2() x 25500) super calendered sulfltepaper with an air iknife coating machine to give a release papercarrying a l to 1.5 lbs. per ream (20 x 2,5-500) coating of wax.

RELEASE PAPER B Two parts ofY stearic acid, 3 parts of triethanolamineand 10 parts of AC-Polyethylene-629 (Semet-Solvay Co.) an oxidized,emulsifiable grade of low molecular weight polyethylene, are melted at-100" C., then poured into 40 parts of boiling water and chilled withagitation. The resulting emulsion is coated on a Z6 lb. (2O x 25-500)supercalendered sulfite paper under conditions to give a coating weightof 1-2 lbs. per ream (20 X 25-500).

RELEASE PAPER C p Two parts of stearic acid, 3 parts of triethanolamine,and 10 parts of Cardis 320 (Warwick Wax 0o.), an oxidized, emulsiiiablemicrocrystalline wax, are melted at `95400" C., then poured into 40parts of boiling water and chilled with agitation. The resultingemulsion is applied to a 26 lb. (20 x 25-500) supercalendered sulfitepaper to Vgive a coating weight of 1 2 lbs. per ream (7.()l x 25-500').

RELEASE PAPER D Release paper D consists of a commercial stockcornprising a 30 lb. kraft paper coated with a 1/2 mil layer ofpolyethylene. Thispaper can be obtained from the International PaperCo., New York, N.Y.

The transfer layer comprises a uniform mixture of a crystalline wax anda synthetic, thermoplastic, film-forming resin. The ratio may varybetween 85% by weight of resin to 15% wax and 15% resin to 85% waxdepending on the specific wax and resin selected. Sufficient -resinshould Vbe used to provide adhesion and freedom from distortion whilesufiicient wax should be used to provide a lowered activationtemperature and sharp breakaway at the boundary of the heat application.Breakaway properties can be visually determined while adhesion willgenerally be satisfactory if the label is not removed when pressuresensitive tape is adhered thereto and stripped off.

The resin and wax comprising the transfer layer should be uniformlymixed and be substantially incompatible, that is, exhibit low mutualsolubility at temperatures below the melting point of the wax. Abovethis temperature compatibility of the resin and wax is controlledthrough selection of the types and ratios of ingredients to` givetransfers of either the hot peel or the cold peel type.

'Mixtures of` resin and wax possessing substantial compatibility abovethe melting point of the wax will exhibit cold pee properties. The termcold peel" indicates that the release backing can be removed after thetransfer has been Vaccomplished and after the system has cooled. Suchtransfers are useful for semiautomatic application and in doublelabeling where the release paper can serve as a temporary top label forpremium offers or coupon use'.

Mixtures of wax and resin which exhibit low compatibility attemperatures above the melting point of the Wax possess hot peelcharacteristics, that is, the release backing can be' removedimmediately after transfer while thetransfericoating Yis still hot.VSuch transfers are particularly useful for'h'igh speed machineapplication.V The breakaway properties of these transfers are believedto be due to the -gelleddiscontinuity of the resin component due to thepresence of the wax.

Compatibility properties of various resin-Wax combinations can beevaluated in a number of ways. Combinations incompatible above themelting point of the wax show little tendency above such temperature toswell or solvate and are gelatinous and cloudy, while compatiblecombinations swell or solvate, soften, become iluid and non-gelatinousand, if unpigmented, are transparent.

Preferably the resins utilized in the transfer layer are syntheticpolymers which are principally organic, linear, thermoplastic, lmforming, substantially water-insoluble and which have second-ordertransition temperatures below 60 C. The term thermoplastic is used inthe conventional sense of being essentially solvent-soluble, softened byheat, and to involve only a minor amount or no cross-linkage. As usedherein the preferred limit of cross-linking is defined in Example Vbelow. The term linear limits the preferred polymers to polymers ofmonofunctional addition-type monomers and difunctional condensation-typepolymers and suitably compounded ester and ether derivatives ofcellulose. As illustrated in the examples below, the transfer layer canincorporate emulsifying agents, plasticizers and other modifyingmaterials without adverse effect.

Second order transition temperature is used herein to indicate thetemperature range of a few degrees at which the properties of rigidity,the coethcient of thermal expansion, the heat capacity, the dielectricconstant, and others, change markedly. Polymer systems are preferred forthis invention which have second order transition temperatures belowabout 60 C. Many pure polymers yhaving such transition temperaturesabove 60 C. can be rendered suitable by plasticization andcopolymerization techniques which reduce the resultant transitiontemperature to 60 C. or below and this invention includes suchmodifications, Example VIII sets forth, by example, the preferred upperlimit of second order transition temperatures.

Synthetic resins which are preferred 4for the present invention includepolyvinyl acetate, polyethyl -acrylate, polymethyl acrylate, polyethylmethacrylate, polypropyl methacrylate, polybutyl methacrylate,styrene-butadiene, acrylonitrile-butadiene, polychloroprene rubbers,polyvinyl butyral, ethyl cellulose, and polyvinyl acetate-vinyl stearatecopolymer.

The wax component should be a material which derives its crystallinitymainly from the presence of long hydrocarbon chains and should melt overa relatively narrow range between the temperatures of about 50 C. to ll0C. Its penetrometer value (ASTM D5-52) when tested with 100 grams for 5seconds at 25 C. should be below yabout l5. Waxm suitable for thepresent invention include beeswax, candelilla wax, carnauba wax,hydrogenated castor oil, montan wax, paraffin wax, low molecular weightpolyethylene, oxidized microcrsystalline wax, and hard wax orderivatives thereof obtained from the Fischer-Tropsch synthesis.

T-he invention may better be understood by reference to the followingexamples which illustrate the preparation of transfer layer coatings.Unless otherwise indicated, all parts and percentages are by weight:

Example I An emulsion of hydrogenated castor oil, M P. 86 C.,penetration 2 (100 g., 5 sec., 25 C.) is prepared as follows: 30 partsof hydrogenated castor oil, 70 parts of water and 2 parts of Duponol Dpaste (E. l. du Pont de Nemours & Co.), an emulsifying agent consistingof the sodium salt of unsaturated long-chain alcohol sulfate, arebrought to a boil and passed through a tightly set homogcnizer. Theemulsion is then chilled with agitation. rIlhe final transfer coatemulsion is prepared by blending 30 parts of the hydrogenated castor oilemulsion with Example Il Example III Ten parts of a 50% solids polyvinylacetate-vinyl stearate copolymer (Air Reduction Chemical Co.) and 20parts of a proprietary hydrogenated castor oil emulsionl (Lukon Emulsion284.3) are mixed and coated on Release Paper A.

Example lV Ten parts of Resyn 12KO3 a vinyl acetate copolymer (NationalAdhesive Div. of National Starch Products, Inc.), l0 parts of R.B.H.Titanium Dioxide Dispersion 223E57 and 30 parts of the hydrogenatedcastor oil emulsion described in Example l are blended and applied toRelease Paper C.

Example V Ten parts of Vultex PX-20-A (General Latex & Chemical Co.) a30-35% emulsion of a copolymer of 55% butadiene and 45% acrylonitrileand 30 parts of a proprietary 30% hydrogenated castor oil emulsion(Lukon Emulsion 284.3) are mixed and coated on Release Paper A.

Example VI Ten parts of Vinylite XY HM (Bakelite Corp), a mediumviscosity polyvinyl butyral and 30 parts of Duroxon C-60t-A (DuraCommodities Corp), a hard, oxidized Fischer-Tropsch wax `are dissolvedin hot butanol and applied to Release Paper D.

Example V111 Ten parts of dry solid polymer obtained by drying RhoplexB-60-K emulsion (a 46% flexible acrylic polymer emulsion sold by Rohm &Haas Oo., Philadelphia, Pennsylvania) and 15 parts carnauba wax, MP.83-86" C., penetration of l (100 grams, 5 seconds, 25 C.) were dissolvedin parts methyl ethyl ketone with warming.

Example VIII Fifteen parts of montan wax, M.P. 70-85 C., penetration g.,5 sec. 25 C.) of 9-10, and l0 parts of the dry polymer from RhoplexB-60-K Rohm & Haas) are dissolved in 90 parts of warm methyl ethylketone and applied -to- Release Paper D.

The above transfer coatings are applied to the release paper backing togive a dry coating weight of from 3 to 7 pounds per ream (20 x 25-600)of release paper which yields a dry coating from `0.4 to 1.0 mil inthickness. The paper can be coated with conventional paper coatingmachinery as an emulsion, a solvent solution, or as a hot melt. Emulsionapplication is generally more satisfactory and for this purpose, thecomponents should be in a tine state of subdivision. t

'Ihe Vadhesion of the transfer layer of the present invention is derivedlargely from the polymeric component which should therefore be selectedto show specic adhesion for the film to be decorated. For examplepolyvinyl acetate, polyacrylates and Buna N rubbers possess specificadhesion to moistureproof cellophane and polybutyl methacrylatepossesses adhesion for vinyl film and rubber hydrochloride.

Printing on the transfer coating can be accomplished by conventionalprocesses such as letterpress printing, rotogravure and exography. Mostcommercial inks are '7 satisfactory for this purpose although commercialinks used to print directly on film of the type to be transfer decoratedis preferred. The following formulation of well known ingredients isgiven as a typical example of a letterpress ink useful Ifor heattransferrlabeling heatsealable cellophane and cellulose acetate film:

Lbs. Phloxine toner 4.0 Lithol Red 3.5 Red Lake C 2.0 ASynthetic varnish40.0 Cobalt lineoleate 1.0

Since many commercial inks do not exhibit the desirable sharp breakwaycharacteristics of the transfer layer, the designs should be arrangedsuch that the edges of the heating surface register with uninkedportions of the transfer layer.

As a specific procedure the fol-lowing example is given. The releasecoating of Example I above is coated on Release Paper A to give a drytransfer coating of from 4 to 5 pounds per ream (20 x 25-500). Thecoated side is then printed with a glossy oil ink from a naturalletterpress plate. After the ink has dried a section of the transfercoating carrying the ink image is transferred to heat-scalable,moistureproof cellophane by rolling the two stocks, with moderatepressure, over a hot plate at 175 C. The release paper is immediatelystripped away leaving a transfer only at the area where heat andpressure were applied. This coating also exhibits specific adhesion tocellulose acetate iilm and kraft paper.

A particular advantage of the `present invention is that it allowssimple, rapid, economical machine operation. Most packaging machineshandling transparent lms are so constructed that the film, usually inroll form, is fed optionally past a label applicator to a wrapping orbag forming station. The transfers according to the present invention'are fed to the labeling machine which would have proviison forimprinting prices, code numbers, etc., on the composite sheet prior totransfer. Since transfer occurs only at the area where heat and pressureare applied, close alignment is not required.

While the primary purpose of this invention is to provide a heattransfer and a method of applying a design (including printing or artwork or both) to packaging film, the heat-transfers provided herein willtransfer advantageously to other material and surfaces such as wood,paper, ceramics, plastics, metals, glass and the like and such use isincluded within its scope. It is also obvious that the transfer layerinV this invention may be transparent or may be dyed or pigmented to anydesired color,

may bc applied a discontinuous layer only in the shape and' position ofthe desired label to permit easy hand operation where this is desirable.Further it is obvious that, where desirable, the design can be appliedto the outer surface of packaging film or other objects in which casethe transfer 4layer will be unpigmented to permit the VVdesign to belegible therethrough.

It should be understood that the present disclosure Yis for the purposeof illustration only and thatthe invention includes yall modificationsVand equivalents which fall VWithin the scope ofthe appended claims.

l claim:

l. A heat transfer for applying a printed design to thin impervious iilmwhich comprises a backing and transfer layer thereon, said transferlayer comprising a uniform mixture of a crystalline wax and a synthetic,thermoplastic, film-forming resin whereinV each ingredient is present tothe extent of at least of their combined weights, said film-formingresin constituting theV major resinous ingredient in said layer, saidresin and wax being substantially incompatible at temperatures below themelting point of the wax, said layer being receptive to printing,strongly adherent to the receiving hlm, non-blocking and having thevproperty of sharp break-away at the boundary of heat application,whereby substantially the whole of said layer within said boundary maybe transferred with a sharp outline and without substantial distortion.

" 2;l A heat transfer according to claim l, wherein said mixture ofresin and wax are substantially incompatible at temperatures both belowand above the melting point of the wax. v

3. A heat transfer according to claim 1 wherein the resin in thetransfer layer is a synthetic, linear, polymeric material which isprincipally organic, thermoplastic, substantially water-insoluble andwhich has a second-order transition temperature below approximately 60C.

4. A heat transfer according to claim 1 wherein the crystalline wax inthe transfer layer has a melting point between about 50 C. and 110 C.and a penetrometer value below about 15 when tested with 1GO gramsweight Yfor Y5Y seconds at 25 C.

5.A A heat transfer Iaccording to claim 1 wherein the transfer layercomprises a plastic resin selected from the group of polyvinyl acetate,polyethyl acrylate, polyniethyl acrylate, polyethyl methacrylate,polypropyl methacrylate, polybutyl methacrylate, styrene-butadiene,acrylonitrile-butadiene, polychloroprene rubbers, polyvinyl butyral,ethyl cellulose, and polyvinyl acetate-vinyl stearate copolymer andcrystalline wax selected from the group of beeswax, candelilla wax,carnauba wax, hydrogenated castor oil, montan wax, parain wax, lowmolecular weight polyethylene, oxidized micro-crystalline wax, and hardwax and derivatives therefrom obtained from the Fischer-Tropschsynthesis.

6. A heat transfer according to claim 1 wherein the transfer layercomprises a uniform mixture of lexible acrylic resin and hydrogenatedcastor oil.

7. A heat transfer according to claim 1 wherein the transfer layercomprises a uniform mixture of polyvinyl acetate resin and hydrogenatedcastor oil. Y

8. A heat transfer according to claim 1 wherein the transfer layercomprises a uniform mixture of polyvinyl acetate-vinyl stearatecopolymer and hydrogenated castor oil.

9. A heat transfer according to claim 1 wherein the transfer layercomprises a uniform mixture of polyvinyl butyral resin and a hard,oxidized wax derived from the Fischer-Tropsch synthesis,

l0. A heat transfer according to claim l wherein the transfer layercomprises a uniform mixture of acrylic resin and carnauba wax.

11. A heat transfer of the cold peel type for applying a printed Ldesignto thin, impervious film which comprises a backing and a transfer layerthereon, said transfer layer comprising a uniform mixture of crystallinewax and a synthetic, thermoplastic, film-forming resin wherein eachingredient is present to the extent o-f at least 15% of their combinedweights, said mixture of resin and wax being incompatible below themelting temperature of the wax and substantially compatible above thistemperature, said layer having the property of sharp breakway at theboundary of heat application, whereby the area of Vsaid layer withinsaid boundary may be transferred with a sharp outline and withoutsubstantial distortion.

12. The method of applying a printed design to a receiving surface whichcomprises coating a backing with a transfer layer comprising a uniformmixture of a crystaline wax anda synthetic, thermoplastic, film-formingresin wherein each ingredient is present to the extent of at least 15%of their combined weights, said film-forming resin constituting themajor resinous ingredient in said layer, said resin and wax beingsubstantially incompatible at temperatures below the melting point ofthe wax, printing ya design on the exposed surface of said transferlayer and transferring said design, together with a supporting filmconstituting substantially the fuli thickness of a predetermined area ofsaid transfer layer which is less than the whole area of said layer, tothe receiving surface by apply-ing heat and pressure to said.predetermined area to eiect transfer of that area with a sharp outlineand without substantial distortion.

13. The method of applying a printed design according to claim 12,wherein said design is applied to thin impervious film.

14. A heat transfer for applying a printed design to thin-imperviousfilm which comprises a backing having a wax-like sizing, a transferlayer on said backing, and a printed design on said transfer layer, saidtransfer layer comprising a uniform mixture of a crystalline wax and asynthetic, thermoplastic, film-forming resin wherein each ingredient ispresent to the extent of at least 15% of their combined weight, saidnlm-forming resin constituting the major resinous ingredient in saidlayer, said resin and Wax being substantially incompatible attemperatures below the melting point of the wax, said layer beingreceptive to printing, non-blocking, strongly adherrent to the receivingiilm, and having the property of sharp break-away at the boundary ofheat application, whereby substantially the whole of said layer withinsaid boundary may be transferred with a sharp outline and withoutsubstantial distortion.

References Cited in the le of this patent UNITED STATES PATENTS1,899,066 Tonge Feb. 28, 1933 1,939,821 Lawrence Dee. 19, 1933 1,941,697Lawrence Jan. 2, 1934 1,968,083 Lawrence July 31, 1934 2,219,071Humphner Oct. 22, 1940 2,275,957 Groff Mar. 10, 1942 2,510,750 MarquardtJune 6, 1950 2,688,579 Meyer Sept. 7, 1954 2,696,452 Trepp Dec. 7, 19542,920,009 Humphner Ian. 5, 1960

1. A HEAT TRANSFER FOR APPLYING A PRINTED DESIGN TO THIN IMPERVIOUS FILMWHICH COMPRISES A BACKING AND TRANSFER LAYER THEREON, SAID TRANSFERLAYER COMPRISING A UNIFORM MIXTURE OF A CRYSTALLINE WAX AND A SYNTHETIC,THERMOPLASTIC, FILM-FORMING RESIN WHEREIN EACH INGREDIENT IS PRESENT TOTHE EXTENT OF AT LEAST 15% OF THEIR COMBINED WEIGHTS, AND FILM-FORMINGRESIN CONSTITUTING THE MAJOR RESINOUS INGREDIENT IN SAID LAYER, SAIDRESIN AND WAX BEING SUBSTANTIALLY INCOMPATIBLE AT TEMPERATURES BELOW THEMELTING POINT OF THE WAX, SAID LAYER BEING RECEPTIVE TO PRINTING,STRONGLY ADHERENT TO THE RECEIVING FILM, NON-BLOCKING AND HAVING THEPROPERTY OF SHARP BREAK-AWAY AT THE BOUNDARY OF HEAT APPLICATION,WHEREBY SUBSTANTIALLY THE WHOLE OF SAID LAYER WITHIN SAID BOUNDARY MAYBE TRANSFERRED WITH A SHARP OUTLINE AND WITHOUT SUBSTANTIAL DISTORTION.